Cuemath
Cuemath: Metric System
Learn more about the metric system by taking a look at the common metric units along with some solved examples and a few practice questions to test your understanding.
Wikimedia
Wikipedia: Metrication in Canada
Outlines the reasons Canada converted to the metric system, the process through which this happened and the impact on various professions and industries.
Other
Wfp Consulting: Si Navigator
A commercial site which has links to many SI/metrics sites. It gets you to a host of sites. Don't hesitate to use it for research.